An aftertreatment system treats exhaust gas from an engine before the exhaust gas flows into the atmosphere. The aftertreatment system uses a reductant, such as ammonia, urea, and/or the like to convert nitrogen oxides (also referred to as NOx) present in the exhaust gas into other molecules, such as nitrogen, water, carbon dioxide, and/or the like. The aftertreatment system may include a reductant injector that sprays the reductant into a mixing tube of the aftertreatment system as the exhaust gas flows through the mixing tube. This mixes the reductant into the exhaust gas while the exhaust gas flows through the mixing tube. A selective catalytic reduction (SCR) module, using one or more catalysts, converts the nitrogen oxides in the exhaust gas after the exhaust gas exits the mixing tube and flows into the SCR module.
In some cases, one or more factors may reduce the effectiveness of the aftertreatment system to treat the nitrogen oxides in exhaust gas. For example, a backpressure may be created by the exhaust gas flowing through the aftertreatment system, which may inhibit a flow of the exhaust gas to the catalysts in the SCR module. As another example, the reductant and exhaust gas may not be homogenously mixed before exiting the mixing tube, which decreases the capability of the SCR module to convert the nitrogen oxides in the exhaust gas.
One attempt to reduce backpressure in an aftertreatment assembly is disclosed in U.S. Patent Application Publication No. 2015/0315948 that published on Nov. 5, 2015 (“the '948 publication”). In particular, the '948 publication discloses a modular aftertreatment assembly that experiences a reduced amount of backpressures due to a split flow design that includes two banks of catalysts. In particular, the '948 publication discloses an aftertreatment assembly having a single central inlet end that receives and introduces exhaust gases into a mixing tube that includes slots at an outlet end. According to the '948 publication, the slots facilitate mixing of the exhaust gases and a reductant as the exhaust gases and reductant exit the mixing tube and allow the exhaust gases to exit the mixing tube without biasing a first and a second bank of catalysts. Per the '948 publication, the provision of two banks of catalysts leads to the doubling of catalyst faces, which in turn reduces the amount of back pressure experienced by the aftertreatment assembly.
The exhaust gas aftertreatment system of the present disclosure solves one or more problems faced by the aftertreatment assembly of the '948 publication and/or other problems in the art.